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標題: | 單分散硫化鉛量子點的優化: 侵蝕動力的協同效應 Optimization of Monodisperse PbS Nanocrystals: Synergistic Effect on Etching Kinetics |
作者: | 鄺文揚 Wen-Yang Kuang |
指導教授: | 周必泰 Pi-Tai Chou |
關鍵字: | 硫化鉛,量子點,侵蝕動力,鹵素侵蝕,協同效應, lead sulfide,quantum dot,PbS QD,etching,synergistic effect,homogeneity, |
出版年 : | 2023 |
學位: | 碩士 |
摘要: | 硫化鉛量子點(PbS quantum dot)技術商業化的可行性取決於大規模生產方法 的研發,並且此大規模生產方法必須確保高品質的產出。到目前為止,Jianbing Zhang 等人研發的升溫方法(heat up method)在眾多非熱注入合成法(non-hot injection method)中擁有最佳的表現,實現了在粒徑為 2.2 至 4nm 大小區間中 6 至 7%的粒徑分佈(size distribution)。 然而,此方法合成出來的粒徑分佈會隨著粒徑 的增加而惡化(>4nm)。為了在 PbS 量子點的大規模生產方法中實現高度粒徑集中 性,我們對 PbS 量子點上鹵素離子的侵蝕動力型態(etching kinetics)進行了深入 探索。我們在機制的探索始於觀察 PbS 量子點在不同濃度的鹵素離子下的生長演 變,使我們發現了一個有趣的現象:在 3.05-4.55nm 量子點尺寸範圍內的平均侵蝕 速率(average etching rate)在極低濃度鹵素離子的環境下經歷了意外的劇降。這種 現象違背了由表面積對體積比(surface-to-volume ratio)主導的常規侵蝕動力型態。 值得注意的是,這種異常動力型態產生了有利的協同效應(synergistic effect),從 而實現優化出一系列具有優化粒徑分佈的量子點尺寸的策略。
我們提出了一個利用這種機制的合成後優化處理程序(post-synthesis procedure),以提供更好的粒徑一致性(size homogeneity)、增益的光學特性以及尺 寸可調性。該處理程序著重於兩個主要方面。首先,此方法主要機制在於打造出最 佳的侵蝕環境,通過優化侵蝕配體(etching ligand)的加入量以確保誘發出所需的 蝕刻動力型態和足夠的蝕刻能力。第二,此方法致力於有效地抑制由鹵素離子促進 的奧斯特瓦爾德熟化(Ostwald ripening),卻又同時保留鹵素離子必要的活性以達 成高效的侵蝕過程,這目標是我們透過以最佳的鉛與油酸比例(lead-to-oleic acid ratio)添加油酸鉛,並且進一步透過逐滴添加油酸來試圖維持此一最佳比例來達成 的。 總結下來,我們首次深入探究了鹵素離子引起的尺寸集中效應背後的潛在機 制。基於侵蝕機制的暸解,我們開發了一種簡單的優化程序來生產一系列不同尺寸 的 PbS 量子點,並且實現了 5 至 6%顯著優化的粒徑分佈。 The commercial viability of lead sulfide quantum dots (PbS QDs) technology hinges on the development of reliable large-scale production methods that ensure high-quality output. Until now, Zhang's heat up method has demonstrated the most promising performance for large-scale production of PbS QDs, achieving a size distribution of 6- 7% (2.2-4nm). However, the size distribution deteriorates with increasing particle sizes (>4nm). In an attempt to achieve high homogeneity in large scale production of PbS QDs, we conducted an in-depth exploration of the etching kinetics of halide ions on PbS QDs. Our investigation began with the observation of the growth evolution of PbS QDs under varied concentration of halide ions, leading us to uncover an intriguing phenomenon: the average etching rate on the QD size range of 3.05-4.55nm experienced an unexpected plunge at exceedingly low concentration of halide ions. This phenomenon defied the conventional etching kinetics dictated by surface-to-volume ratio. Significantly, this anomalous kinetics gave rise to a synergistic effect, leading to strategies that achieve a series of CQD sizes with optimized size dispersity. We presented a post-synthesis protocol capitalizing on this mechanism to offer a better size homogeneity, enhanced optical characteristics and broad size tunability. The protocol focuses on two main aspects. Firstly, it focuses on creating an optimal environment for etching, ensuring the desired etching kinetics and sufficient etching capacity by optimizing the amounts of etching ligands. Secondly, it aims to effectively suppress the detrimental Ostwald ripening process facilitated by halide ions, while preserving their necessary activity for an efficient etching process. This is achieved by adding lead oleate in an optimized lead-to-oleic acid ratio and maintaining it through the dropwise addition of oleic acid. In summary, for the first time, we have conducted a comprehensive investigation into the underlying mechanism behind the size focusing effect induced by halide ions. Building upon this understanding, we have developed an advanced optimization procedure to produce PbS QDs having a remarkable size dispersity of 5-6% across various sizes. |
URI: | http://tdr.lib.ntu.edu.tw/jspui/handle/123456789/88473 |
DOI: | 10.6342/NTU202301853 |
全文授權: | 同意授權(全球公開) |
顯示於系所單位: | 化學系 |
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